i HYMENOPTERA : Family EULOPHIDAE.

WASH., VOL. 23, N'O. 5,

MAY,

REMARKS ON THE GENUS PLEUROTROPIS WITH DES( RIPTION OF A PARASITE OF TRACHELUS TABIDUS FABRIC

IIS.

i

H YMENOPTERA

^:

(H ALCIDOIDE

A._j

Bv A. B. GAHA.V, Bureau ofEntomology.

The

occurrence of the exotic sawfly, Trachelus tabidus Fahricius, ⁱⁿ

America

as a possibly serious pest ^of

wheat was

brought to light during ^the

summer

of 1918.

A

_paper

_by

the writer treating of^thissawfly has already been published

by

^the U. S.

Department

of Agriculture.¹

Mention

is

made

in this article of the rearing

by Mr.

^{\V. R.}

McConnell

of a parasite belonging ^{to the} genusPleurotropis

and

_apparentlyrepresenting an undescribed species.

Inviewof the foreign origin of the host^{it is}naturaltosuspect,

though

the conclusion does notnecessarily follow, that thepara-

site too is exotic. ^It has

proved

impossible to reconcile the insect withthe description of

any

exotic form,however,

and

asit

does not

conform

to

any

^described

American

_species it

seems

desirable to describe it.

Inthe process of identifying^thisspecies the writer

was

ledinto

making

^a

^more

^{or lesscarefulstudy of} the characters, especially those of the antennae, appertaining ^{to the} genusPleurotropis.

The

results ofthis study ^arediscussed herewith.

Family EULOPHIDAE.

Subfamily Entedoninae.

Genus

PLEUROTROPIS.

Pleurotropis Foerster,Hymen. ^Stud.II,1856,p. 78.

Pseudacriasoides Girault, DescriptionesStellarumNovarum,1917,p.^9.

Epipleurotropis Girault, Descriptiones Hymenopterorum Chalcidoidicarum cum Observationibus, 1917, p. ^7.

The two

_genera^{listed as}

synonyms

^{are based}

upon

^characters which, ^after examination of the types, ^I can not accept ^as generic.

Pseudacriasoides has as typePleurotropis utahensis Crawford.

The

_generic description by ^{Girault is as follows:}

"Antenna

9-jointed, three ring-joints, the club 2-jointed;

male antenna

1((.jointed, three ring-joints, the club 2-jointed, the scape dilated. Scutellum with a

median

sulcus at base. Otherwise

likePleurotropis.'"

Pleurotropis ^utahensis'1-

was

described from four female

and

six

male

_specimens ^of

which

the holotype

was

reared at Salt

Lake

Cir\ , I tah, from

Agromyza

parvicornis mining ^{the leaves} of corn, while the allotype

and

all paratypes were ^reared from

Bul. 834,U.S. Dept.Agric., 1920, 18 pp.

2Proc.U. S.Nat. Mus.,^vol.45, 1913,p.316.

114 PROC. ENT. SOC. WASH., VOL. 23, NO. _5,

MAY,

¹⁹²¹

Cephas

^sp. (subsequently

determined

as

Cephus

^cinctus

Norton)

boring ^thestems ofwild grasses

and

_grain atSalt

Lake

_City

and

Kimballs,

Utah.

In addition to the type ^{material there are}

now

ⁱⁿ the National collection eleven specimens ^reared

from Cephus

^{cinctus at Missoula,}

Montana, and

determined

by

^the writer asPleurotropis utahensis.

The

different host recordsfor theholotype

and

theparatypes are

ground

^forsuspicion that the^latter

may

represent^adifferent species. If _so, however,

Mr. Crawford who _compared them when

describing the species ^{failed tofind} characters to separate them.

Apparently

^also

Mr.

_Girault,

who saw

allof the material, accepted ^{itas all} belonging^{to the}

same

_species. Otherwiseit is to be

presumed

^{that he}

would have

_proposed a

new

_specific

name

for the paratypes. After a careful re-examination ofall the material

and

_despite the antennal differences discussed later, the writerisstillofthe opinion ^thatall represent the

same

species.

As

in all such cases

unsupported by

^careful biological studies the question ^of

whether

one or

more

_species isrepre- sented in a given ^lot ofmaterial is merely ^a matterof personal opinion.

FIG.1 Pleurotropis utahensis Crawford. A, B, C, and D, ^female antennae illustratingvariations. E,male antenna.

As shown _by

the

accompanying

figures

which

illustrate

antennae

taken

from

tour different females

and mounted

in

balsam

^thereisconsiderable variation ⁱⁿ theantennalcharacters

WASH., VOL. 23, 5,

MAY,

in this lot of material. Figure 1,

A

is

from

the holotype;

B

from a paratype;

C and D

from

two

of the Missoula,

Montana,

specimens.

Except

^for the differences in antennae the _speci-

mens

are inseparable,

though

differing

somewhat

in size.

A

glance ^{at the} figures will

show

that the differences lie in the relative closeness of the union

between

_joints 8

and

9 of the

antenna and

the degree ^of

development

^{of a} suture dividing joint 9 into

two

_joints.

The

relative size

and

_shapeof the joints

ispractically the

same

for allfour antennae. In _figure

1-D, we have what

_appears to be a 2-jointed ^funicle

and

a 3-jointed club. In C,joints ⁸

and

9 are not _{nearly so closely} united

and

the suture dividing the ninth is not so distinct. This

antenna may

^be said either to

have

a three-jointed ^tunicle

and

a two- jointed club, or a two-jointed ^funicle

and

a three-jointed club, the interpretation

depending

entirely

upon

the individual

mak-

ing the examination. Figures

A and B

arealike

and

differ

from C

_only in the apparent absence^ofthesuture dividing the ninth joint.

Although

^the greatest care

was

exercised in

making

^these

mounts

there can be little

doubt

^{but that} to

some

extent the apparent differences are to be accounted for

by

^the imperfect definition of

subopaque

objects

when mounted

ⁱⁿ balsam.

Careful examination, ^before

mounting,

^{of the}

antennae from which

_figures

A and B

were

made showed both

to

have

adefinite

though

very delicate constriction near the apex corresponding inposition^tothesuture dividing theninth_jointinfigures

C and

D.

When mounted on

aslide thissuture

was

_entirelyinvisible.

The

antennal

mount made _by

Girault

from

the holotypespeci-

men and upon which

^{he based his} description of the genus Pseudacriasoid.es

was removed from

the slide

and

it too

showed

a distinct constriction or shallow groove

on

the ninth _joint.

When remounted

in

balsam

this groove again

became

invisible, correspondingⁱⁿ appearance to figure

A which was drawn from

the other

antenna

of the

same

_specimen.

The

pressure of the cover _glass probably accounts ^to

some

extentforthe greaterseparation

between

_joints⁸

and

9_{in figures} A, B,

and

C. Joint ^{8 is} apparently

more

orless

cup-shaped

^at apex, the base_{of joint 9} fitting into the aperture.

The

articu- lation

between

the

two

_joints is free nevertheless,

and

not anchylosedas are the club _joints.

Antennae

from the

same

_specimens are not always exactly alike in respect ^to the characters in question.

For

_example, while _figure

B shows

the ninth _joint without a dividing suture the other

antenna from

the

same

^individual

when mounted

ⁱⁿ balsam

shows

a

more

or less distinct suture. Also the

mate

to the

antenna from which

_figure

D was drawn

_appears to

have

joints ⁸

and

9

more

_{distinctly separated.}

Whether

one or

more

than one _species is represented ^{in this}

116 PROC. ENT. SOC. WASH., VOL. 23, NO. _5,

MAY,

¹⁹²¹

material, ^it affords a

good

illustration of the _folly of basing genera

upon

^suchslightdifferences inthe antenna.

The

mater-

ial

under

consideration, as already pointed out, hasbeen

exam-

ined

by

^{three different students of} Chalcidoidea

and

_accepted

by

^{all three as} a single species.

Yet from

an examination of slide-mounted antennae _alone, the four individuals,

antennae

of

which

are _figured,

would

_probably be run in

any

^{of the} existing generic keys ^{to three different} genera.

The

_genera to

which

_they

would

be assigned

would depend

largely

upon whether

theindividual

making

^theexamination chose tocallthe eighth antennal_joint apart of the club or apart ^{of the}funicle,

upon how many

^{of the}

^minute

ring-joints he

was

able _{to see,}

and upon ^whether

^{or not the} particular

mount examined

revealed the suture dividing the ninth _joint.

The

determina- tion of the generic position

would depend

^{to a} considerable extent

upon

the individuality of the particular specimen

from which

the

antenna

for

mounting was

^{taken but}

more

_largely

upon

the accidents of

mounting.

The antenna

of the

male

allotype of Pleurotropis utahensis (Figure ^1, E) ^is ten-jointed.

The

_scape is only slightly

more

dilated than in typical species of the genus.

The

_flagellum

tapers

from

base to apex

and

the club is hardly differentiated

from

the funiclealthoughjoints 9

and

10 are

more

or lessanchy- losed

and

_{probably represent} the club. If so the funicle is

3-jointed ^{as in} typical Pleurotropis.

There

are three distinct

though minute

ring-joints.

Most

writers

have

credited the genus Pleurotropis with only one ring-joint.

Waterston

_(Bull. Ent. Research, ^vol. 5, 1915, p. 343) considers the ringa singlejoint butstates that thisjoint consists of

two

to three laminae

which

are distinctly separated only ventrally.

With

this conception ^I can not wholly agree.

Mounts

^of antennae

from many

of the species ⁱⁿ the National collection

have

been

examined

withtheresult thatin

most

cases

ithas been _possible torecognize three completering-joints. In

some

cases there are apparently only two, ^{while in a} few in- stances

owing

^tothe positionⁱⁿ

which

the

antenna was mounted

it

was

_impossible todetermine the

number. The

ring-jointsare always

more

orless telescoped intoeach other but areseparated both

above and

below.

When

the flagellum ^is bent

upward

^it tendsto pull thering-joints apart ventrally whilepressing

them more

_closely together dorsally

and

this

may

^{account for the}

impression gained

by

^Waterston.

It is the writer's belief that while Pleurotropis normally has ten-jointed antennae in both sexes consisting of scape, pedicel, three ring-joints, a 3-jointed ^funicle

and

a 2-jointed club, the genus can not be ^{limited to this} antennal formula because one finds ^all degrees of separation

and

solidification of the apical

two

or three joints ofthe flagellum, ^{it is} not always possible ^to

WASH., VOL. 23, 5,

MAY,

determine

whether

certain joints are ^a part^of theclub or a part of the funicle,

and

one can seldom be absolutely certain ^{as to} the exact

number

of ring-joints ^{in a} given antenna,

While

theseantennaldifferences,withincertainlimits,are

undoubtedly

ofimportance as specific characters their use as generic charac- ters can only ^{result in} adding confusion ^to a situation that is

already tangled enough.

Disregarding ⁱⁿ large part the antennae

and

recognizing ^as the essential features of the genus ^the medially ^bicarinate

propodeum,

togetherwiththose othercharacters ascribedto the genus

by

Waterston, ^will bring together a natural

group

^of species

which may

^be easily recognized

and

_readily defined.

The _group

^will include species having widely ^different types ^of antennae, ranging

from

those having ^four ring-joints, a 2- jointed ^funicle

and

a solid club, as ⁱⁿ the

male

ofclisiognatluis Waterston, ^{to those} having

two

ring-joints, four _distinctly pedicellated funicle joints,

and

a solid club as in the female of atamiensis

Ashmead. The

fact that antennaeof the

two

sexes of the

same

_species not infrequently exhibit such widely ^differ- ent characters as illustrated

by Waterston

in the species clisiognathus^isproof

enough

^{that antennal}characters arenot of generic value in this group.

The

scutellar character referred to

by

^{Girault for the} genus Pseudacriasoides isofeven less value than the antennal charac- ters.

The

_alleged

median

_{groove on} the base of scutellum is

nothing

more

thanaveryslightlongitudinal depression

marking

thelineofconvergenceof the sculpturefromthe

two

sides of the scutellum. In

some

_specimens it does not appear^{at all.}

Epipleurotropis Girault ^is based

on

Epipleurotropis longfel- lowi Girault, thetype material ^of

which

consists of a_single

male specimen

^the

head

of

which was removed by

the describer

and

crushed beneath a cover _glass.

The abdomen

is missing.

Judged by what

remains ofthis specimen ^{this is a distinct}

and

well

marked

_species but not sufficiently different to warrant separation

from

Pleurotropis.

The

scutellum is

smooth

medially

and

mostly^so laterally but witha

narrow

longitudinal depressed ^line of sculpture on each side, appearing ^{as a} shallow groove.

The propodeum

^{does not differ}

^from

ordinary ^Pleuro- tropisexcept ^{that the}medial

cannae

are _slightly less

prominent

than usual.

The

mandibles are bidentate with the inner

margin

^exhibiting

two

or three fineserrations, a character

com- mon

to a

number

of species of Pleurotropis ^as pointed ^our by

W

^7aterston.

The

antennae areof the

same

_type as the

male

of Pleurotropis utahensis.

Pleurotropis benefica, new_species.

Apparently

closely related^toPleurotropisnigritarsis

Thomson

but _differing

from

the description of that species principally ⁱⁿ

118 PROC. ENT. SOC. WASH., VOL. 23, NO. _5,

MAY,

¹⁹²¹

antennal characters. Also similar to Pleurotropis utahensis

Crawford

but is readily distinguished

from

that species

by

^the

dark

_tarsi,

by

the relatively longer

and more

_hairy antennal joints,

by

^the

more

_{strongly sculptured}

and

differently colored front of the head,

and by

slight differences in the

propodeum and abdominal

_petiole.

Female. Length ³

mm.

Head slightly broader than the thorax; vertex ratherflat,separated fromthe occiput by ^asharp^carinatemargin,and closely and _strongly punctate;^{ocelli in} an obtuse _triangle, the lateral ocelli removed from the eye-margin about the long diameter of an _{ocellus;occiput} concave, opaquely sculpturedwith a smooth linemedially; eyeslarge, sparsely clothed with whitish _hairs, deeply emarginate ^within and less strongly so behind;

posterior orbits stronglypunctate andclothedwith rather coarse darkcolored hairs;malarspace short,about equalⁱⁿlength^totheantennalpedicel; front of theheadinflexed,abovethe transversegrooveshiningwithshallow reticulations, betweenthe transversegrooveandbase ofantennaecloselyand_deeplypunctate and_{subopaque,just}belowthebase ofantennae weaklyreticulatedand_shining, moath-borderfinelyopaquely punctate; antennae 10-jointed, inserted slightly

FIG. 2 Antennaeof PleurotropisbeneficaGahan. A, male; B,^female.

above the lower eyemargins and _separated at base by ^{a distinct} ridge; scape slender, slightlycurvedandmoreor less flattenedand shining metallicon the outer _{side, sculptured} and darker on the inner side with seven to eight erect hairson the ventralmargin;pedicelabout twice as long^as thick; three small transversering-joints; flagellarjoints^alldistinctly hairy;^firstfuniclejoint^dis- tinctly the longest, about three times as long as thick; second alittle thicker than thefirst and approximatelytwice as long^as thick; third aboutaslong as thickandalittlemore_{closelyjoined}tothe following jointthantothe preceding;

club 2-jointed,aboutequalⁱⁿ length^to thesecond funicle joint, the basal club joint subquadrate and ^as broad as the _funicle, second or apical joint much

narrower,conical,incompletely separated from the basal jointand terminating in ashort butdistinct spine; pronotum^{above with anarrow} smooth_posterior

WASH., 23, 5,

MAY,

margin^{set off}by acarina fromthe anteriordeclivous portionwhich^issculptured;

mesoscutum strongly punctate, the parapsidal grooves complete and each terminating posteriorly ^{in a} large foveiform depression, the surface within the depression ^as strongly sculptured ^as the remainder^of mesoscutum; ^scutellum much _longer than _{broad,sculptured} like the mesoscutum, except thaton the anterior half of scutellum the punctures ^are somewhat smaller; ^axillae above sculptured ^like mesoscutum, ^below much more finely punctate; propodeum polished, themedian carina forked alittlebehind the middle, the ^{lateral folds} straight and well developed, spiracular furrows deep; posterior ^lateral argles of thepropodeumproduced^intoashort triangular tooth-like process justabove the attachment of the hind _coxae; mesosternum nearly smooth, ^the median groove terminating anteriorly ⁱⁿ afoveiform enlargement; abdomen not quite as long ^asthehead and_{thorax,pointed}ovate; petiolelarge,broader than_long, opaque,carinatelymargined laterally,above and below,and with the anterior margin produced dorsally into ^ashort flangewhich overlaps the posteriorend of thepropodeum;^secondsegmentcomprising aboutone-third the length of the abdomen, smoothbasally, the apical halfweaklyreticulated; thirdandfollowing tergites ^allfinelysculptured,subopaque, anddistinctly thoughsparsely hairy;

thirdtergiteaboutone-thirdaslong^asthe second; fourth^tosixthsubequaiand each abouttwo-thirdsas long as thethird;seventh approximatelyequal ^tothe third;ovipositor concealed;submarginal^{veinof the}forewingdistinctly^lessthan half as long^asthe verylong marginal,withtwoor three upright black ^bristles above; proximal end ^{of the} marginal ^vein with a similar bristle, also; post- marginal and stigmnl veins short and _subequai. General color bright bluish- green:head darker thanthethorax withthe occiput black,andthefaceblackish, except that the area just below the insertion ofantennae ^is coppery and the triangular area above the transversegroove ^is slightly more bluish; antennae entirely metallic black; legsconcolorous with the thorax, their tarsi brownish black; second _tergite bright blue-green; the petiole and _segments beyond ^the second brownish-black; wingshyaline, the venationdark brown.

Male. Length ^2.2

mm.

Antennae 10-jointed, scape slightly and _nearly uniformlythickened,aboutfour timesaslong^as thick; pedicelnotmuch_longer thanthick; threering-jointstransverse; flagellum longerbut nomore_hairythan inthe female;^firstfuniclejoint four times,second twoandone-half times,and the thirdslightlymorethan twiceas long^as thick; fourthjointbarely twice as long^asthick; clubsolid,aboutaslong^asthesecondfuniclejointand terminating ina distinct spine;abdomenshort, thesegmentsbeyond the fourth retractedami mostly concealed;petiole longerthan _broad, almost aslong ^as thehind coxai-,

and withoutdistinctmargn.al^carinae. Otherwise like the female except that the head isfor themost _partconcolorous with the thorax,onlythe occiputami a transversepatch on ^{the vertex}embracingthe posterior^ocellibeing black.

Type-locality.

Mount

_{Holly Springs,} Pennsylvania.

Type. Cat.

No.

_24,166,

U/S.

Nat.

Mus.

Host. Trachelus tabidus Fabricius.

Eleven females

and

four males reared

by W.

R.

McConnell,

April 13 to 19, 1919,

from

hibernating prepupal larva of the black grain-stem ^sawfly

and

recorded in the

Bureau

^of Ento-

mology under Webster No.

^18,700; one female paratype ^reared

120 PROC. ENT. SOC. WASH., VOL. 23, NO. _5,

MAY,

¹⁹²¹

at_Carlisle,Pennsylvania,

by

^{C. C.}Hill,April20, 1919,

from

the

same

_host;

and

one

male paratype

^reared

by

^{P. R.}

Myers,

April 30, 1919,withthe

same

_locality

and

host.

Antennae

oftype

and

allotype

mounted on

a slide.

Mr. McConnell

states that the species ^{is a}

primary

parasite

and

that only a single individual ^is obtained

from

a host larva.

DISTRICT OF COLUMBIA DIPTERA: SCATOPSIDAE.

BY W. L. McArEE.

These

smallto

minute

blackflies

have

long been placed^{in the} Bibionidae,but

seem

better

grouped

^asaseparatefamily.

They

breed ⁱⁿ decaying vegetable matter

and

in excrement; ^{in the} adult stagethey^are

most

_easily

found

inflowers

and on windows.

The most

useful

American paper on

^the family ^{is that of}Dr.A.

L.

Melander

(Bui. 130,

Washington

Agr.

Exp!

St., April, 1916).

Itisbased

on

a

European

revision ofthegenera

by

G. Enderlein (Zool. Anz. Vol. 40, pp. 261-282, October, 1912). In the last

named

paper genera ^are

founded

on _triflingdifferences in vena- tion

which may

not prove whollysatisfying; ^{in fact} one of

them

is

synonymized on

^asubsequent page.

Other

_{genera of}

Ender-

lein's areused butit

must

be

admitted

that incertain casesonly a little variation

would

link

them

_up.

The

_{only genus} here treated that has a distinct habitus isAspistes.

Key^tothegenera.

A. Front tibiaending ^inadecurved sharp pointedprocess;thorax_strongly elevated anteriorly, the declivity coarsely punctured; wing ^without apical cell,^i. e., anterior branch of fourth vein interrupted basally.

Aspistes.

AA. Without the preceding combination of characters.

B. Anteriorbranchof fourth vein stronglyangulate near base or emitting a crossvein which extends _part way ^or entirely ^to third vein Scatopse.

BB. Anteriorbranchof fourth vein neitherangulatenor emitting a^cross- vein.

C. Apical wing ^cell present.

D. Apical ^cell much shorter than itsstalk Swammerdamella.

DD. _Apical cell longerthan itsstalk.

E. Lastvein ofwing^{with a}singlecurve; vein 3remote from costa, section from radial crossvein to costal margin strongly curved intowing;^{radialcrossvein} near middle ofsecond vein; subcostal^cellusually larger than_costal;

halteres white; hind tibiae abruptly expanded distally

..Reichertella.